Introduction: Trefoil family factor 3 (TFF3) is a small polypeptide first described in the intestine, characterized with unique structure of trefoil motif, a 40-amino acid domain that contains three conserved disulfide bonds. TFFs have a well established role in the process of restitution after mucosal injury and the maintenance of epithelial barrier integrity, moreover their role in other systems started to emerge. In a recent study TFF3 gene was identified as one of the genes involved in liver steatosis (1). The aim of this study was to determine the rate of monounsaturated fatty acids in the liver of Tff3 knock-out mice, as well as the serum glucose and lipid content.Materials and methods: Tff3 knock-out (129/Sv) and wild type (129/Sv) mice (n=20 per group) were bred at the Animal Facility of the Faculty of Medicine Osijek (Croatia). Care and use of the animals and the experimental protocol were reviewed and approved by the local Ethics Committee. Mice were anesthetized at the age of 5 weeks by 75 mg/kg of ketamine and 0,5 mg/kg od midazolam and the blood was collected by cardiac puncture. Following mice were sacrificed by cervical dislocation and the liver tissues collected and snap frozen in liquid nitrogen or fixed in 10% formalin and processed for regular histological analysis (HE, PAS). Total lipids were extracted from tissue homogenates according to Bligh and Dyer. Lipids were converted to methyl esters with 0.5 M KOH in methanol for 20 min at RT and analyzed by gas chromatography (Varian 450-GC equipped with a flame ionization detector) using a capillary column Stabilwax at a programmed temperature with helium as the carrier gas. Serum lipids and glucose were analysed in routine laboratory using Architect c8000 (Abbott Diagnostic). Results: Tff3 knock-out mice compared to WT mice have significantly lower amount of monounsaturated acids in the liver (14.64±2.02% vs. 26.31±2.48%; p<0.0001; Figure 1A). Total serum levels of the cholesterol, triglycerides, HDL or LDL cholesterol (Figure 1C) did not differ among the groups. Postprandial glucose levels in Tff3 knock-out mice were higher than in controls but did not reach statistical significance (p=0.072; Figure 1B). There were no differences in the total body weight or the liver mass. Microscopic analysis of the liver sections revealed normal tissue architecture (HE) and glycogen reserves (PAS).Conclusion: Lack of Tff3 gene resulted in reduced rate of monounsaturated acids in the liver with no impact on serum lipids. However, this may have resulted in impaired insulin sensitivity and slightly increased postprandial serum glucose levels in Tff3 knock-out mice.